1. Field of the Disclosure
The disclosure relates to a system having a drivable component of a drive for a control element, such as a final control element like a valve, and a movable motion representative to be driven by the component. Furthermore, the disclosure relates to a position sensor for detecting the position of a drivable component of the drive for a final control element. In addition, the disclosure relates to a device for regulating the position of a final control element drivable by a drive. Finally, the disclosure relates to a drive for a final control element and a method for detecting the position of a drivable component.
2. Related Technology
A known position sensor, such as a potentiometer, is frequently used in an actuator, such as a lift and pivot drive, which may, for example, bring the actuating element of a valve into an open or closed position and/or into intermediate positions. In order to achieve desired operating parameters of the operating system to be influenced by the actuating element, such as a fluid circulation for petroleum or gas processing, a position regulator is provided which adjusts the position of the actuating element. The position sensors are implemented for the purpose of determining the precise position of the actuating element in order to provide an actual position signal to the position regulator to determine an actual state.
The position of the actuating element is calipered or monitored in a known way via a motion representative, which follows the motion of the actuating element because of a mechanical coupling between the motion representative and the component. The representative motion of the motion representative is detected by the position sensor.
Forming the mechanical coupling between the drivable component and the motion representative through engagement devices including a pin and oblong hole or tongue and groove arrangement is known. This type of connection typically has play, particularly for easy assembly, which may be compensated for by using a spring which provides a pre-tension. Providing the spring not only increases the manufacturing outlay because of the additional part, but also carries a risk of breakdown for the position sensor and therefore for the control loop, because expansion of the assembly play occurs, which can be amplified by breakdown of the pre-tension spring, particularly in the event of frequent load alternation, which may lead to loosening and, in some circumstances, to detachment of the mechanical connection. In addition, mechanical connections, particularly for use in chemical facilities, paper factories, or the like, are typically subjected to an aggressive surrounding medium, which encourages corrosion, vibration, and contamination of the individual parts. The mechanical couplings are therefore completely encapsulated in an area of use of this type, which also increases the manufacturing costs and, in addition, makes maintenance and/or repair of the sensor system difficult and, in some circumstances, less cost-effective than complete replacement.
Position sensors are usually housed in a position regulator housing, which is positioned neighboring a prime mover of an actuator, the motion representative projecting through the housing toward the component to be driven and being attached thereto to transmit force. In order to ensure rapid and easy replaceability of the position regulator, the motion representative must have an easily detachable transmission connection to the driven component of the actuator.
Using a direct sensor system, in which the position of the drivable component, particularly the actuating rod or the actuating shaft, is monitored directly at the component, is also known. This direct sensor system, which may be implemented by a Hall sensor, for example, is unsuitable for use in valves in particular, however, because a non-linearity of the measurement result is connected therewith, which may only be linearized via high pre-mounting outlay. The additional outlay is expressed above all in necessary reference measurements, which may be implemented using a mechanical clock gauge, which must be installed and uninstalled before beginning operation to determine reference variables. These measures are necessary upon each replacement of a sensor system.